Last days of Earth: Timeline to the end of everything

The first living molecules appeared 3.8 billion years ago and on current estimates, the last cells will be snuffed out in another 3 billion years. Along the way, several factors could have huge consequences for what survives and where

4 May 2016

		3.8 billion years ago The spark of life animates molecules for the first time
		3.5 billion The first cells form in water, somewhere
		2.4 billion Photosynthesising bacteria start coughing oxygen into the atmsophere
		2 billion The first complex cells are 鈥渂orn鈥� 补苍诲鈥�
		1.5 billion 鈥ivide into three groups: the ancestors of plants, animals and fungi
		650 million years ago Tiny jellyfish are the first complex animals. Some say sponges came first, but recent genetic evidence suggests not
		575m Weird animals called Ediacarans appear and persist for about 33 million years
		565m Fossilised trails suggest some animals are moving under their own power
		530m Backbones evolve in the first true vertebrates, as part of the Cambrian explosion
		500m Fossils suggest our ancestors had crawled onto land by now
		465m They were followed by plants
		400m Then insects聽and quadrupeds
		340m Then amphibians
		250m Early dinosaurs make an appearance
		150m Archaeopteryx takes to European skies
		130m Flowers!
		65m Bye bye dinosaurs, hello mammals
		25m Apes split from monkeys 7-6m Our ancestors split from chimps and bonobos All of humanity fits in this box 200,000 years ago Homo sapiens stands up and walks out onto the African savannah 鉃OU ARE HERE Humans colonise every corner of the planet 800,000 years ahead If we have the same lifespan as other big mammals, we go extinct. But extra smarts and technology could give us more time If, by some remarkable feat, Homo sapiens or its descendants manage to keep going for hundreds of millions of years, the soaring temperatures would start to be a real problem. Humans could perhaps buy even more time by building a planetary sunshade, or (why not?) pushing Earth out of orbit
500 million years ahead Water world scenario Earth鈥檚 core cools and plate tectonics grind to an early halt. Mountains stop rising, and erosion flattens most of them within 20聽million years. As erosion flattens the land, the oceans start to flood the continents. Remaining peaks become refuges for life. Elsewhere, only marine life survives. Plants die as CO₂ levels fall		500 million years ahead As the sun gets hotter, rising temperatures boost silicate rock weathering (see main story). As a result, more and more CO₂ is sucked out of the atmosphere. Plants struggle to photosynthesise and start to die. With plant food becoming scarce, the great animal die-off begins Large mammals are first, followed by small mammals, then birds, amphibians, large fish, reptiles, small fish, until only marine invertebrates and microbes remain. Battered by rising temperatures and radiation, life goes through a renewed evolutionary explosion. Completely new life forms could arise
800m The last mountains are eroded. Earth becomes a water world. Without nutrients flowing off the land, even marine life starts to go extinct
		900m CO2 levels drop below the minimum needed for plant life. Only microbial photosynthesisers are left. For a while, insects that can eat dead plants will hang around, but soon only creatures that don鈥檛 need plants can survive. Tube worms feed off chemicals from underwater hydrothermal vents. Tardigrades could eat bacteria and other, smaller, tardigrades
1 billion The sun is 10 per cent brighter than in the 21st century. The average temperature is 47鈥壦欳. Oceans start to evaporate. Only microbes survive. Go to 3 billion		1 billion The sun is 10 per cent brighter than in the 21st century. The average temperature is 47 掳C. Oceans start to evaporate. This spells the end for even the hardiest animals. For the first time in about 4 billion years, Earth is a microbial world
		1.1 billion CO2 levels fall so low that even microbial photosynthesis ends. Some microbial life marches on, using energy from chemical compounds rather than light
		1.2 billion The equator becomes too hot for the microbes still clinging on in pockets of water. They are extinguished first at sea-level鈥�
1.5 billion Tilted planet scenario The moon has been slowly moving away, and by now it is causing Earth鈥檚 axis to swing. Earth settles at an extreme tilt. Some regions are protected from the sun, temperatures dip below 100 掳C for part of the year, and some cave systems even have liquid water year-round. Even deeper down, it freezes, and in these cold-trap caves microbes survive for more than a billion years		1.5 billion 鈥hen at the tops of equatorial mountains
		1.85 billion It鈥檚 now getting too hot even at the poles. Microbes start to die in sea-level pools鈥�
		2.2 billion 鈥nd then at altitude. The surface is now sterile. Underground, microbes stick around for a little while longer
2.8 billion On the tilted planet, even the deepest caves have become too hot for life. Microbes in the subsurface hold on for another 200 million years
		3 billion 3 billion 3 billion Evaporating oceans cause a runaway greenhouse effect. Temperatures rocket. Even microbes deep beneath the surface cannot hold out. Earth becomes sterile
		4 billion The heat is now great enough to melt rock
		7.5 billion The sun expands to become a red giant. Soon after that, Earth and the moon are engulfed by it. The sun鈥檚 habitable zone shifts to the outer solar system. Saturn鈥檚 moon Titan might just warm up enough for life to evolve. Maybe